1. Field of the Invention
The present invention relates to a method for producing an acidic milk beverage which has stable properties and undergoes less sedimentation or separation of whey during product storage.
2. Related Art
Conventionally, acidic milk beverages containing live bacteria, such as fermented milk, have widely been consumed as health-promoting beverages having physiological activities such as activity that promotes intestinal health and immunopotentiating activity. Also, since a culture liquid (fermented milk) of lactic acid bacterium or biffidobacterium has a unique flavor, it is sterilized and used for production of acidic milk beverages.
Acidic milk beverages as described above are desirably stable and undergo less sedimentation and less separation of whey. Stability of lactic acid bacteria beverages is intimately related to casein protein, one of the components of milk. When the pH of the product approaches 4.6, which is the optimum pH of casein protein, molecules of casein protein coagulate and precipitate, forming sediment at the bottom of the container, or separation of whey. From this, reducing pH of acidic milk beverages to a value far less than 4.6 is considered desirable. However, in view that milk beverages having a pH value of less than 3.5 have poor flavor, the above approach of reducing pH has limitations. Thus, in order to stabilize acidic milk beverages, currently, homogenization or addition of a stabilizer is generally performed. As stabilizers, pectin and carboxymethylcellulose (CMC) are used. However, use of these stabilizers may impart a viscous tint to the product, rendering an unfavorable texture in terms of flavor. In addition, pectin and CMC are problematic in that they gelatinize the product within a low pH range.
Japanese Patent Application Laid-Open (kokai) No. 7- 59512 discloses that stable acidic milk beverages which do not provide unfavorable pasty sensation can be obtained by subjecting dairy products such as milk to fermentation by lactic acid bacteria in the presence of water-soluble hemicellulose originating from soybeans (hereinafter referred to as a soybean polysaccharide). However, soybean polysaccharides have relatively weak stabilizing power, and therefore, addition thereof in small amounts cannot attain satisfactory stabilizing results; whereas addition in large amounts increases production costs and impairs flavor of the acidic milk beverage.
Stability is well known to depend on the concentration of solid matter, or in other words, on product viscosity. That is, the higher the viscosity, the greater the effect of suppressing coagulation of casein protein, to thereby improve stability. As the solid matter, a sweetener such as sugar is generally used. However, in order to meet recent, mounting demands resulting from consumers"" keen awareness of nutrition which call for low calorie products and beverages having light flavor, sugar and other sweetening agents which have heretofore been used have come to be used in smaller amounts. This also places limitation on stabilization of products achieved by increasing the content of solid matter.
In view of the foregoing, the present inventors have conducted extensive studies, and have found that when water-soluble hemicellulose such as a soybean polysaccharide is used as a stabilizer in the production of an acidic milk beverage, and two or more steps of homogenization treatments are performed at specific stages of the production process, there can be obtained an acidic milk beverage which is endowed with excellent stability and remarkable texture, thus leading to completion of the invention.
Accordingly, a general object of the present invention is to provide an industrially advantageous methodxe2x80x94which has minimal effect on product flavor and texturexe2x80x94for producing an acidic milk beverage providing no unfavorable pasty sensation and exhibiting excellent storage stability.
In one aspect of the present invention, there is provided a method for producing an acidic milk beverage, characterized by homogenizing fermented milk, then adding water-soluble hemicellulose thereto for mixing, followed by an additional step of homogenization.
In another aspect of the present invention, there is provided a method for producing an acidic milk beverage, characterized by homogenizing fermented milk, then adding thereto a mixture of water-soluble hemicellulose and a dairy product for mixing, followed by an additional step of homogenization.